I have had a similar problem with a Sony SAT-A2 DSS receiver with RF remote; it was placed within four feet of both a Panasonic phone system and a burglar alarm box. I was never able to kill those things to see if the interference went away, but I used my signal meter, located the frequency of the Sony remote (around 318 mHz), then "sniffed" around with a short wire antenna; the phone system and/or alarm were definitely the culprits. I could not move the DSS so I had to convert to Xantech XtraLinks from four different rooms.

Another time, I had the same Sony DSS model near one of those Sony receivers with the "egg" RF remote; the remote control antennas for the two components had to be about four feet apart for both components to work properly. Apparently, while the remote antenna is built beautifully to receive RF, RF garbage that is generated inside the component is not blocked from radiating from the antenna!